Hmmm. Let me make sure I have all the info here. You are running Win7 English with an English keyboard (anything unusual about it and how many keys? Manufacturer?) which is software emulated to be either English or Russian, right?

First, while I've been away for several weeks, I haven't heard of any bug (on Windows) like this before for any language. That leads me to think it's something specific to your setup. My first guess is your hardware -- the kind of keyboard and the drivers. Do you have any other pointing devices also connected? Next, when you switch from H to Z, do you press or press-and-hold the key? Do you have any sticky-key setting enabled? Do you get this in both US and Russian mode? Can you repro fairly easily?

I have a quite similar problem. If I zoom in any opended file (pressing cmd&space keys and the mouse to select the desired area) in about 80% of all cases the tool does not return to the one I had selected before. Instead it switches to the hand tool. I cannot even switch back. I have to repeat zooming out and in again, until the tool-selection works again. This drives me crazy.
I already reset the preference file but it still happens.
I have Photoshop CS6 (13.0.6 x64) on an iMac with 32GB RAM, Mavericks on it. The problem also existed with the previous MacOS. It does not occure, if I only use cmd&+ or cmd&- to zoom in and out.
Do you have any idea?
Thanks, Daniel